1. Technical Field of the Present Invention
The present invention generally relates to integrated circuits and, more specifically, to circuits that perform dynamic circuit timing synthesis and monitor critical paths and environmental conditions of the integrated circuit.
2. Description of Related Art
The design of integrated circuits has become increasingly difficult as a result of numerous challenges. One particular challenge has been the ability to predict the cycle time (i.e. the time interval between the start of one cycle and the start of the next cycle) of large-scale integrated circuits. In recent years, this has become progressively complicated from various factors (e.g., scaling) that increase the variation in process, across-chip line width, and response to environmental conditions.
The most common solution for this challenge is to add sufficient margin to the cycle time in order to account for the worst-case variation in timing that can occur as a result of either process or environment variables. Unfortunately with shrinking cycle-times and increasing process variations, the usable portion of the cycle-time has also been decreasing. In other words, cycle time should not be dominated by the design margin, and therefore, cycle times must be increased which reduces the available performance of an integrated circuit in a given technology. Another solution has been to dynamically adjust the cycle-time of an integrated circuit during its operation so as to take full advantage of the available cycle-time (dynamic voltage and frequency scaling). Unfortunately, this technique requires calibration of each integrated circuit at every desired operating point, and this unnecessarily consumes valuable test time.
It would, therefore, be a distinct advantage to have a circuit that would accurately predict the cycle time of an integrated circuit while it is operating. This would allow dynamic voltage and frequency scaling to maximize performance of the integrated circuit at all operating points. The present invention provides such a circuit.